Low reading on a couple of my dash guages

My 89 f150 reads low on both the ammeter and the temp guage. The ammeter barely reads 12 volts, even at driving speed with a new alternator, and the temp guage reads about a 1/4 off of cold, and I have a new 195 deg thermostat. It's not a big deal, but I would prefer they were accurate in case there is an issue. The oil pressure guage and fuel guage seem to be fine. Anything besides the fact that they're old guages come to mind? Thanks